(a) Field of the Invention
The present invention relates to fueling systems for vehicles, and, more particularly, to a CNG-vehicle fueling system having a lubricant drainage device for preventing infiltrated lubricant from causing system elements not to function properly.
(b) Description of the Related Art
The use of natural gas as an alternative fuel for motor vehicles has economical and ecological advantages because natural gas is less costly and cleaner burning than gasoline or diesel. However, use natural gas as a fuel for a motor vehicle, a CNG fueling system must be provided for the vehicle.
FIG. 5, shows a conventional CNG fueling system. As shown in FIG. 5, the conventional CNG fueling system including a CNG tank 102 and a flow line 104 which connects the CNG tank 102 and an internal combustion engine (not shown in the drawing), along which a high-pressure regulator 106 for regulating high-pressure gas from CNG tank 102, a solenoid valve 108 which is opened or closed according to signals from a electronic control unit (ECU), a low-pressure regulator 110 for regulating low-pressure gas, a gas mass sensor 112 for detecting the amount of the gas flow, and a flow controller 114 for adjusting the gas introducing into the engine. The CNG tank 102 is also provided with a connector 116 to be connected with a gas charger.
However, the CNG fueling system has drawbacks in that when charging the CNG, lubricant infiltrates into system elements such as the low-pressure regulator 110, the gas mass sensor 112, the flow controller 114, and even into a combustion chamber of a vehicle engine due to the high charging pressure. This lubricant infiltration can cause system elements not to function properly. Accordingly, engine performance deteriorates, especially related to the generation of toxic has due to the combustion of these infiltrated lubricants in the engine.